5-(chloromethyl)-2-furaldehyde (CMF) is a furan based platform chemical derived from six carbon carbohydrates by the action of concentrated hydrochloric acid. CMF has been the subject of numerous publications concerning both its formation from biomass, as well as its use as a flexible platform molecule for creating specialty fuel and fuel products. While the chemistry of producing halogenated methyl furfurals had been examined (see, e.g., M. Mascal, Pat. US007829732 B2, 2010) a production scale system for producing CMF from saccharides in a pure or crude form has not yet been described.
The formation of CMF from cellulosic and hemi-cellulosic biomass (saccharides in a pure or crude form) also yields a by-product, which has been identified as a precursor to Hydrothermal Carbon (HTC), or Hydrothermal Carbon (HTC) itself. The size of HTC particles range from about 5 nm to about tens of micrometers (agglomerated) in diameter. When producing CMF, these particulates reside in both aqueous and organic phases of the reaction medium, making isolation of pure CMF difficult.
A practical, but not production scale, continuous flow system for creating CMF has been described by Brasholz (see, e.g., M. Brasholz, K. von Kanel, C. H. Hornung, S. Saubern and J. Tsanaktsidis, Green Chem., 2011, 13, 1114); however, this study did not address the scale and repeatability limitations that prevent such a system from being utilized as a production scale system. The system described in Brasholz includes several limitations that are addressed in the present invention.
Mascal in US 2009/0234142 describes a method of producing CMF. Mascal teaches a batch reaction, wherein polysaccharide and an aqueous acid are introduced to a reaction vessel, and then organic solvent is added continuously to the vest. Mascal accordingly teaches a method that allows continuous extraction of formed products from a batch reaction. All of Mascal's examples teach the batch reaction proceeding for 30 hours, while reaction products are removed and organic solvent is added either continuously or at intervals of from 1 minute to 12 hours. Mascal teaches a single step of cooling a reaction mixture for preparing HMF from CMF. Mascal, in an example of production of 5-methylfurfural, teaches the use of aqueous sodium bicarbonate to quench previously added hydrochloric acid. Mascal's methods unavoidably produce 5-(hydroxymethyl)furfural (HMF), 2-(2-hydroxyacetyl)furan (HAF) and levulinic acid (LA) as by products of the degradation of CMF.